But for Sir'mone McCaulla and Christopher Gutierrez, what should've been a brief collision outside a post office in a crowded part of town took a violent turn this week, and both men are now dead: Gutierrez, stabbed to death on the street, McCaulla in an apparent suicide after the altercation.
Both were headed home after long day; both had toddlers. Both had a troubled past they were struggling to make right, and that male swagger that comes with being young and growing up on the street, according to friends and relatives.
They bumped shoulders walking past each other along Eighth Avenue across the street from Madison Square Garden at about 5:45 p.m. Sunday. Gutierrez had just finished his shift stocking groceries at Met Food and was headed to his new apartment in Queens. McCaulla had just gotten off a bus from New Jersey and was on his way to see his daughter in East Harlem.
Words were exchanged and they squared off. Gutierrez took of his jacket and, from surveillance video of the incident, it looked like he aimed to start a fist fight.
"I told the man 'keep it moving, no problems, but if u (sic) leap I'm gonna (sic) f--- you up,'" McCaulla wrote in a rambling post on his MySpace page.
McCaulla had a knife at his side, and he lunged at Gutierrez, stabbing at him four times, according to Police Commissioner Raymond Kelly. He struck Gutierrez in the chest and he fell bleeding onto the steps of the James A. Farley Post Office.
Surveillance tape shows a man walk slowly away, then turn around and go back to the scene to pick up a cell phone before disappearing into the crowd. A German man snapped a photo of the suspect and gave it to police.
The investigation into the slaying began, and Gutierrez's family started to grieve.
"He was a good boy. So young. Trying to get his life in order and he was doing a good job," said Daisy Perez, a relative who raised him from birth.
As a teen, Gutierrez attended Green Chimneys, a farm upstate for emotionally troubled children that encourages work with animals. By all accounts, he had turned his life around in the past year, gotten a job and moved into his own apartment.
He had a son, Eric, about to be 2 years old whom he'd never met but was planning to visit in Pennsylvania, his family said. Instead, the toddler saw only his father's casket as he padded around the funeral home located a few blocks from where the family lived.
"He was struggling so hard to get back on his feet, to do right. It was so stressful for him," said Perez, wiping tears from her eyes. "We used talk about how he wanted to be a cop, an undercover cop."
McCaulla had been an Army reservist since 2003, and had apparently been in Kuwait. He said he was in training to be a corrections officer. He had a 3-year-old girl, Samirah, and was recently fired from a job as a FedEx driver.
McCaulla disappeared after the incident, and his mother, Arlene, told reporters earlier in the week she hadn't seen her son in several days and felt in limbo.
Police said McCaulla went to the home of his ex-girlfriend in Philadelphia, where he electrocuted himself in the bathtub. His MySpace posting was entitled: "My statement b4 goodbye," and he said he was venting and wasn't going to correct his spelling.
"I didn't mean to kill him just wanted to stop the threat," he wrote. "I'm goin (sic) out rather go out in the hands of myself than another man if it's hard for me to find work out of the arm its gonna (sic) be 10 times harder if I come out as a felon."
His body was found Wednesday. An autopsy is pending in Philadelphia, and his family has apparently gone there, according to neighbors outside their East Harlem home.
Gutierez's family members say they don't hold a grudge against McCaulla.
"His family is suffering, like ours," said Daisy Perez. "It's just so awful. How many times do knock someone on the street? And nothing happens. You step on the wrong person's sneakers and you're dead. It's senseless."